Rotary speed changer



May 5, 1959 l P. R. PITAYTMANJR 2,834,815

' ROTARY SPEED CHANGER Filed Feb. 25, 1956 2 Sheets-Sheet 2 United States Patent i ROTARY SPEED CHANGER Paul R. Pittman, Jr., Dayton, Ohio, assigner to `Globe Industries, Inc., Dayton, Ohio, a corporation of Ohio Application February 23, 1956, Serial No.- 567,128 4 Claims. (Cl. 'i4-i804) 'amount' of power which the assembly is capable of transmitting.

Another object of this invention is to providev a'ro'tational speed changer in which the number of stages of speed reduction can be easily increased by merely increas'ing the axial length ofthe assembly.

`Another object of this invention is to provide a-rotary spted changer having a minimum numberv of moving pav` s.

Other objects and advantages reside in the construction of parts, the combination thereof and the mode of operation, as will Ibecome more apparent from the following description.

In' the drawing:

Figure 1 is a perspective view of a rotary speedchan'ger ofth-isinvention.

Figure 2 is an enlarged side sectionalview 'of' a'rotary speed changer of this invention.

Figure 3 is a sectional view taken substantiallyfon `line 3-3 of Figure 2.

Figure 4 is a sectional view similar to that of Figure 3 but with parts brokenaway.v Figure 4 shows the movable elements of the invention in positions thereof ditferprises a hollow cylindrical housing. or annular gear 10 lwhich is provided with an end plate 12 atone end thereof and an end plate 14 at the other end thereof. The end plates 12 and 14 are attached to the cylindrical housing 10 by any suitable means such as by screws or bolts .16.

The cylindrical housing or annular gear 10 is provided with a plurality of radial teeth 20 which extend axially within the annular gear 10.

An input shaft 22 is rotatably supported by an anti- `friction bearing 24 mounted within the end plate 12. The

input shaft 22 extends within the housing or annular gear 10 and is substantially concentric therewith.

The input shaft 22 may be rotatively driven by any suitable means. Firmly attached to the input shaft 22 2,884,815 Patented May 5, 1959 ice within the housing 10 and rotatable therewith is an eccentric member in the form of a circular disc or cam 26. Ro tatably carried within the annular gear 10 by the cam 26 i's' a follower member 30. The follower member 30 is provided with a plurality of teethtor projections 32. Preferably, the teeth 32 are disposed at opposite portionsof the4 follower 30. Herein, the number of teeth of the fol: lower is shown asY being two in number; however, a greater number of teeth may be provided. Y y I Theteeth 32 are" adapted tovmesh with the teeth 20 of the cylindrical housing 10. However, as the cani member 26 rotates with rotation of the shaft 22', vthe cam member 26 moves the follower member 30 in a reciprocal manner so that each' of the teeth32, as shown in Figures 3 and alternately engage the teeth 20 of the housing 10. During each engagement ofV one of the teeth 32 withthe teeth 20 of the housing 10, las the cam 26 rotates, the cam 26 moves the follower 30 slightly in a direction normal to the teeth 32. Thus, there is pivotal movement of the follower 30about each tooth 32 which is in engagement with the teeth 20. This' pivotalkv movement of the follower 30 with rotation of the cam 26 -results in slight rotational movement of the follower 30 so'- that each tooth 32 of the follower 30 moves from one tooth 20 of the housing 10 to an adjacent tooth 20 of the housing 10, with each revolution of the cam member 26; Therefore, the input shaft 22- must rotate through a number of revolutions equal to the number of teeth 20 in the annular gear `10 in order t'o cause one revolution of a follower 30. Thus', a first stage of rotational speed reduction is provided. v

' In order to transmit the' rotational movement of the follower' 30 to another rotatable element, any suitable is formed in the follower member 30. rI'he slot 34 is adapted to receive an axially extending pin merrlbei` 36.

The' pin` member 56V is attached to an intermediate member 38 which is herein shown in the form of a wheel, but may be in the form of an arm or any `other suitable shape. The intermediate member 38` may be attached to a suitable output shaft when only one stage `of rotational speedl reduction is desired. However, herein, a two stage reduction unit is shown.

' The' intermediate member 38 is' integrally attached to a hub member'40, which is rotatably carried by' the input shaft 22. Integraily attached to the hub 40 in axiaialignment with the intermediate member V38, acaxn'vrnember 42 which is similar te the cam member 2 6. Rotatable iabout the cani 42 is a second follower member 44, shown in Figures 2 and 5.- t u v The follower member 44 is similar to the follower 30 and is' provided with 'a plurality of teeth or projection members 45 disposed at opposite portions thereof. Rotation of the cam member 42 causes reciprocal and rotational movement of the follower 42 ina mannerisimilar to that described with respect to the follower 30. The

i follower 44 rotates the distance from one of the teeth 2.0

`ofthe cylindrical housing 10 to. an adjacent tooth 20 `upon each revolution of the cam 42.

The follower 44 is provided with a radially extending slot 46 into which an axially extending p-in member 48 is slidably movable. The pin member 48 is rigidly attached to a connector member in the form of an arm or wheel 50. The arm or wheel 50 is firmly attached to an output shaft 52 which is rotatably supported in the end plate 12 by means of an anti-friction bearing 54. Therefore, the output shaft 52 is driven by the input shaft 22 through two stages of speed reduction.

In Figures 1, 2, 3, 4 and 5, as shown, the ratio of rotatonal speed between the input shaft and the output 3 shaft is equal to one divided by the square of the numberA of the teeth 20 in the cylindrical housing.

It is to be understood that by changing the amount of eccentricity of the cam members 26 and/or 42, the amount of rotational movement of the followers 30 and/ or 44 with each revolution of the cams may be changed. In other words, by changing the amount of eccentricity of the cams, the followers may be caused to move more than one tooth during each revolution of the respective cam members.

Figures 6 and 7 show in enlarged detail a modification of this invention. These figures clearly show the reciprocal and rotational movement of a follower mermber 60 which is driven by means of a cam member 62. The cam member 62 is rigidly attached to a shaft 64. .The follower member 60 rotates within a housing or annular gear 65, provided with internal radial teeth 6'6.

The follower member 60 is provided with teeth 68, which are positioned at opposite portions thereof and which are adapted to mesh with the teeth 66.

A pin member 70, slidably movable within a radial slot 72 of the follower 60 is adapted to be attached to any suitable rotational member 74 for rotation thereof with the follower member `60.

lFigures 6 and 7 show in detail, by means of dotted lines, the movement of the follower member 60 during movement thereof from one tooth 66 to another tooth 66 during one complete revolution of the cam member 62.

Thus, it is to be understood that the rotational speed changer of this invention provides means by which a high ratio of rotational speeds between an input shaft and an output shaft may be obtained with an assembly n of small physical size.

Although the preferred embodiment of the device has been described, it will be understood that within the purview of this invention various changes may be made in the` form, details, proportion and arrangement of parts, the combination thereof and .mode of operation, ,which generally stated consist in a device capable of carrying out the objects set forth, as disclosed and de- .ned in the appended claims.

p Having thus described my invention, I claim:

1. A rotary speed changer apparatus comprising a first shaft, a tixedly mounted circular stop member surrounding a portion of said shaft provided with an internal circular gear having its teeth extending inwardly, a follower member eccentrically mounted upon said shaft and within said stop member, the major portion of the .periphery of said follower member being toothless and minor portions thereof in opposed position on the pey .ripheral surface thereof being each formed with at least one tooth, the distance between opposed teeth on said vfollower member being slightly greater than the internal diameter of said `stop member, whereby the teeth of said follower member are thus adapted to mesh with the teethof the internal gear in alternating 4fashion with rst one tooth on. one of said minor portions of said follower vmember meshing with the internal gear teeth followed by a tooth on the opposed minor portion meshing with the internal gear teeth so that said follower member rotates in smooth continuous fashion, a second A shaft, a driven member drivingly coupled with said second shaft, and lost motion coupling means interconnecting said follower member with said driven member and permitting said driven member to continuously rotate at `a speed slower than the speed of said first shaft, the maximum obtainable speed ratio between said two shafts being thus equal -to the reciprocal of the number of teeth of said internal gear.

2. A rotary speed changer apparatus comprising `a first shaft, a fixedly mounted internal ring gear surrounding a portion of said shaft and concentric therewith, an elongate follower bar eccentrically mounted upon said rst shaft and within said gear, the major portion of the periphery of said follower bar being toothless and minor portions in opposed position on the peripheral surface thereof being each formed with at least one tooth, the outer diameter of said follower bar being slightly larger than the internal diameter of said gear, whereby the teeth of said bar are thus adapted to mesh with the `teeth of the gear in alternating fashion Awith first one tooth on one of said minor portions of said bar, meshing with the ring gear followed by a tooth on the opposed minor portion meshing with the internal gear teeth so that said bar rotates in smooth continuous fashion, a second shaft, a driven member drivingly coupled with said second shaft, and lost motion coupling means interconnecting said bar with said driven member and permitting said driven member to continuously rotate at a speed slower than the speed of said first shaft, the maximum obtainable speed ratio between said. two shafts being thus equal to the reciprocal of the vnumber of teeth of said internal gear.

3. A speed reducer comprising a xedly mounted hollow cylindrical housing having internal radial longitudinally extending teeth, a drive shaft within ythe housing concentric therewith, a cam attached to the drive shaft and rotatable therewith and having a surface eccentric therewith, a follower mounted on the eccentric Asurface and rotatable by the icam, the follower having teeth radiating therefrom only at opposite portions thereof, the teeth being adapted to mesh with the teeth of the housing as the follower is reciprocably rotated by the cam, a hub rotatably mounted about but out of contact with the drive shaft, lost motion means interconnecting the hub with the follower for rotation therewith, an output shaft, means for drivingly interconnecting said hub with said output shaft.

4. The speed reducer of claim 3 vwherein the follower has only one tooth at each of said opposed portions.

References Cited in the tile of this patent UNITED STATES PATENTS 2,170,951 Perry Aug. 29, 1939 2,303,365 Karlsen Dec. l, 1942 2,356,914 i Blancha Aug. 29, 1944 2,520,282 Henry Aug. 29, 1950 FOREIGN PATENTS 500,233 Great Britain Feb. 6, 1939 677,052 Germany June 17, 1939 588,423 Great Britain May 21, 1947 

